Energy group E.ON has become the last of the big-six energy suppliers to announce it will increase tariffs this winter.

Its average dual fuel bill will increase on January 18 by 8.7%, with electricity rising 7.7% and gas by 9.4%.

Having pledged in May to keep residential energy prices on hold during 2012, E.ON said the new year rise was necessary due to the price of energy on the wholesale markets and regulatory costs.

E.ON has about 4.8 million domestic customers, but 800,000 of its customers on fixed and capped tariffs will not be hit by the price rise.

From January 18, a typical standard dual fuel customer paying by cash or cheque will see their bill rise by around £110 a year to £1,370.

Audrey Gallacher, director of energy at Consumer Focus, said: "Most industries will pass on rises in costs, but given the low levels of confidence consumers need to be reassured that retail bills, wholesale costs and company profits are in balance."

Rising energy prices have been a major driver of high inflation that has been squeezing households in recent months.

Today's announcement comes after EDF Energy's 10.8% price rise for domestic gas and electricity came into force last week.

SSE, which trades as Southern Electric, Swalec and Scottish Hydro, increased its tariffs by 9% on October 15, while Scottish Power hiked bills by an average 7% on December 3.

British Gas imposed an average increase of 6% affecting 8.5 million customers from November 16 and Npower's average rise of 8.8% for gas and 9.1% for electricity came into force on November 26.

E.ON chief executive Tony Cocker, said: "We have held back from increasing our prices for as long as we possibly could and at the same time have worked hard to reduce our own costs as a business so that our customers can get the best price possible.

"However, some 16 months after our last price increase, we have had to make the difficult decision to increase our prices."